Trophic ecology of Arapaima in Guyana: giant omnivores in Neotropical floodplains

Using stable nitrogen and carbon isotope signatures, we investigated the trophic ecology and identified potential prey fish groups supporting the giant Arapaima within floodplain lakes of the Essequibo River basin in southwestern Guyana. Morphological descriptions of feeding structures and digestive tract are presented together with preliminary data on Arapaima diets. Stable isotope results suggest that algivorous/detritivorous and omnivorous fishes contributed most to Arapaima biomass, and generally, that was consistent with what is known about Arapaima diets. Stable nitrogen isotope ratios for piscivorous fishes in these lakes were higher than nitrogen isotope ratios for Arapaima, indicating that piscivorous fishes are unlikely to constitute a major source of energy for Arapaima. This population of Arapaima has an intestine averaging 1.45 times total body length, relatively small teeth, and numerous, closely-spaced gill rakers. These morphological features, together with isotope data, support our inference that Arapaima are secondary consumers and may be better characterized as omnivores and not top predators.

Utilizando firmas de isotopos estables de nitrógeno y carbón, investigamos la ecología trófica e identificamos los grupos de peces que potencialmente mantienen a la Arapaima en los lagos inundables de la cuenca del río Essequibo, al suroeste de Guyana. Presentamos descripciones morfológicas de las estructuras alimentarias y tracto digestivo de la Arapaima, conjuntamente a datos preliminares de sus dietas. Los isotopos estables sugieren que peces algívoros/detritívoros y peces omnívoros son los principales contribuyentes de la biomasa de la Arapaima, y estos resultados son compatibles con lo que se conoce actualmente de la dieta de la Arapaima. A diferencia, las proporciones del isotopo estable de nitrógeno para peces piscívoros en estos lagos resultaron más altas que los valores obtenidos para el isotopo estable de nitrógeno en la Arapaima. Esto indica que es improbable que sean peces piscívoros los que constituyan la fuente energética principal de la Arapaima. La población de Arapaima estudiada presenta un intestino que promedia 1,45 veces la longitud total del cuerpo, dientes relativamente pequeños, y agallas con branquiespinas numerosas y cercanamente espaciadas. Estas características morfológicas, conjuntamente a los datos obtenidos a través del uso de isotopos estables apoyan nuestra inferencia que la Arapaima es un consumidor secundario y que puede ser caracterizada como un pez omnívoro y no como un depredador mayor.

Occupational carbamate pesticide intoxication in three farm workers: implications and significance for occupational health in Jamaica

The importance of occupational health practice principles in the delivery of health care to the working population is stressed by the authors' management of the an incident of occupational pesticide poisoning. The clinical management of the patients involved, as well as the occupational and environmental health management of that incident, is discussed. An illustrative case report is used to describe an occurrence of carbofuran pesticide poisoning in three female farm workers in Jamaica. This report highlights the implications and significance of this incident in terms of sensitivity of the medical profession to similar occupational health problems